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52.
Dr. Longyu Li Qianming Lin Miao Tang Dr. Andrew J. E. Duncan Prof. Dr. Chenfeng Ke 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(46):10768-10781
The rapid development of additive manufacturing techniques, also known as three-dimensional (3D) printing, is driving innovations in polymer chemistry, materials science, and engineering. Among current 3D printing techniques, direct ink writing (DIW) employs viscoelastic materials as inks, which are capable of constructing sophisticated 3D architectures at ambient conditions. In this perspective, polymer designs that meet the rheological requirements for direct ink writing are outlined and successful examples are summarized, which include the development of polymer micelles, co-assembled hydrogels, supramolecularly cross-linked systems, polymer liquids with microcrystalline domains, and hydrogels with dynamic covalent cross-links. Furthermore, advanced polymer designs that reinforce the mechanical properties of these 3D printing materials, as well as the integration of functional moieties to these materials are discussed to inspire new polymer designs for direct ink writing and broadly 3D printing. 相似文献
53.
Structural Chemistry - The DFT B3LYP/6–31G(d,p) approach is used to study alkene aziridination by azides through catalyzed routes involving a metal nitrenoid intermediate. The catalysts... 相似文献
54.
Large-scale evacuations are a recurring theme on news channels, whether in response to major natural or manmade disasters. The role of warning dissemination is a key part in the success of such large-scale evacuations and its inadequacy in certain cases has been a ‘primary contribution to deaths and injuries’ (Hayden et al., 2007). Along with technology-driven ‘official warning channels’ (e.g. sirens, mass media), the role of unofficial channel (e.g. neighbours, personal contacts, volunteer wardens) has proven to be significant in warning the public of the need to evacuate. Although post-evacuation studies identify the behaviours of evacuees as disseminators of the warning message, there has not been a detailed study that quantifies the effects of such behaviour on the warning message dissemination. This paper develops an Agent-Based Simulation (ABS) model of multiple agents (evacuee households) in a hypothetical community to investigate the impact of behaviour as an unofficial channel on the overall warning dissemination. Parameters studied include the percentage of people who warn their neighbours, the efficiency of different official warning channels, and delay time to warn neighbours. Even with a low proportion of people willing to warn their neighbour, the results showed considerable impact on the overall warning dissemination. 相似文献
55.
A series of enantioenriched six-membered metallocyclic amidomagnesium naphtholates were prepared and used to probe the structure–reactivity/selectivity relationships of heteroleptic magnesium base complexes within asymmetric deprotonation reactions. An effective complex was identified and applied within enantioselective enolisation processes, delivering good levels of enantioselectivity and also revealing key structural requirements for achieving such selectivity. 相似文献
56.
Sayyeda M. Hasan Landon D. Nash Duncan J. Maitland 《Journal of polymer science. Part A, Polymer chemistry》2016,54(14):1300-1318
Porous shape memory polymers (SMPs) exhibit geometric and volumetric shape change when actuated by an external stimulus and can be fabricated as foams, scaffolds, meshes, and other polymeric substrates that possess porous three-dimensional macrostructures. These materials have applications in multiple industries such as textiles, biomedical devices, tissue engineering, and aerospace. This review article examines recent developments in porous SMPs, with a focus on fabrication methods, methods of characterization, modes of actuation, and applications. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1300–1318 相似文献
57.
The He I photoelectron spectrum of CSe2 has been recorded and four of the bands observed assigned to ionization from valence shell levels that correlate well with those found for CO2 and CS2. Weak bands in the spectra of CS2 and CSe2 are assigned to shake-up processes in which electronic excitation of the ion accompanies ionization. 相似文献
58.
59.
Andreja Lesac H. Loc Nguyen Sanja Narančić Ute Baumeister Siegmar Diele Duncan W. Bruce 《Liquid crystals》2013,40(2):167-174
New, bent‐core mesogens are described in which the core of the molecule is a semiflexible, di(4‐aminocyclohexyl)methane spacer. The compounds show nematic, columnar nematic and columnar phases as shown by a combination of X‐ray diffraction and optical microscopy. The potential of these new mesogens as biaxial nematic candidates is considered. 相似文献
60.
Dr. Amy C. Topley Valerio Isoni Dr. Thomas A. Logothetis Dr. Duncan Wynn Dr. Harry Wadsworth Dr. Alex M. R. Gibson Imtiaz Khan Dr. Neil J. Wells Prof. Cécile Perrio Prof. Richard C. D. Brown 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(5):1720-1725
A Resin‐linker‐vector (RLV) strategy is described for the radiosynthesis of tracer molecules containing the radionuclide 18F, which releases the labelled vector into solution upon nucleophilic substitution of a polystyrene‐bound arylsulfonate linker with [18F]‐fluoride ion. Three model linker‐vector molecules 7 a – c containing different alkyl spacer groups were assembled in solution from (4‐chlorosulfonylphenyl)alkanoate esters, exploiting a lipase‐catalysed chemoselective carboxylic ester hydrolysis in the presence of the sulfonate ester as a key step. The linker‐vector systems were attached to aminomethyl polystyrene resin through amide bond formation to give RLVs 8 a – c with acetate, butyrate and hexanoate spacers, which were characterised by using magic‐angle spinning (MAS) NMR spectroscopy. On fluoridolysis, the RLVs 8 a , b containing the longer spacers were shown to be more effective in the release of the fluorinated model vector (4‐fluorobutyl)phenylcarbamic acid tert‐butyl ester ( 9 ) in NMR kinetic studies and gave superior radiochemical yields (RCY≈60 %) of the 18F‐labelled vector. The approach was applied to the synthesis of the radiopharmaceutical O‐(2‐[18F]‐fluoroethyl)‐L ‐tyrosine ([18F]‐FET), delivering protected [18F]‐FET in >90 % RCY. Acid deprotection gave [18F]‐FET in an overall RCY of 41 % from the RLV. 相似文献